a) Field of the Invention
The invention is directed to a device for reducing noise in the human ear having a microphone which picks up the noise and a reproduction transducer to which a noise compensation signal is fed via a compensation circuit which is connected with the microphone.
b) Description of the Related Art
A device of this kind is known from DE-42 00 811-C2. The known device has a headphone with acoustically closed earpieces or shells surrounding the ear. The microphone for picking up noise is arranged upstream of the reproduction transducer so as to be offset relative to the principal center axis of the reproduction transducer. The noise picked up by the microphone is first fed to an amplifier, then filtered and then fed again with amplification to the reproduction transducer which excites a noise signal which is in opposite phase to the noise.
However, the known device does not always operate satisfactorily under certain conditions. For example, the ear-surrounding shape of the headphone results in poor ventilation for the ear which promotes perspiration in the region covered by the headphone, especially since the headphone contacts with a relatively high contact pressure. As a result, the known device is uncomfortable to wear and inconvenient to use.
On the other hand, every human ear, and the external ear region in particular, has a unique shape like human fingerprints. Accordingly, conditions with respect to sound reflection and sound volume will be different for every human ear. As a result, a compensation regulating circuit which has been tuned once to an average ear reflection behavior and sound volume often operates in a less-than-optimal state when used.